(1 attachment)

User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3
Build Identifier: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.4pre) Gecko/20100408 Lanikai/3.1b2pre
Selecting a portion of text and then attempting to paste over it leads to the entire buffer being placed in the cut buffer. Undo undoes, fortunately.
Reproducible: Sometimes
Steps to Reproduce:
1. Select a portion of the text - in the example I will upload, it will be the quoted text as follows:
The purpose of the
token is to make it unnecessary for the resource owner to share its
credentials with the client. Unlike the resource owner credentials,
tokens can be issued with a restricted scope and limited lifetime,
and revoked independently.
2. Copy and Paste the text to the bottom of the message.
Actual Results:
Entire buffer is cleared
Expected Results:
Text should have been pasted at the bottom of the message.
This seems to be reproduceable on this specific message for me. I wonder whether this is at all related to Bug 250539. I will upload the specific example in a moment.

I don't fully understand the description ("buffer is cleared"???), but I have observed disturbing copy&paste behavior for a months/years (pasting makes text disappear) in Thunderbird nightlies on Windows 7. If that's this bug, it's dataloss, and I hope it receives a high priority/urgency.

(In reply to comment #1)
> Created an attachment (id=438054) [details]
> example draft message that causes the problem.
>
> This is the example I mentioned.
Can you attach an example email in .eml format please ?

Sorry- with respect to Comment 3, it was a new message. I was able to reproduce the error just by copying the quoted text and attempting to past it at the bottom of the message. Poof. Entire message gone.